GDScript: Make sure calls don't use return when not needed

modules/gdscript/gdscript_compiler.cpp

@@ -488,6 +488,9 @@ GDScriptCodeGenerator::Address GDScriptCompiler::_parse_expression(CodeGen &code
 			const GDScriptParser::CallNode *call = static_cast<const GDScriptParser::CallNode *>(p_expression);
 			GDScriptDataType type = _gdtype_from_datatype(call->get_datatype());
 			GDScriptCodeGenerator::Address result = codegen.add_temporary(type);
+			GDScriptCodeGenerator::Address nil = GDScriptCodeGenerator::Address(GDScriptCodeGenerator::Address::NIL);
+
+			GDScriptCodeGenerator::Address return_addr = p_root ? nil : result;
 
 			Vector<GDScriptCodeGenerator::Address> arguments;
 			for (int i = 0; i < call->arguments.size(); i++) {
@@ -538,13 +541,13 @@ GDScriptCodeGenerator::Address GDScriptCompiler::_parse_expression(CodeGen &code
 							if (within_await) {
 								gen->write_call_async(result, self, call->function_name, arguments);
 							} else {
-								gen->write_call(result, self, call->function_name, arguments);
+								gen->write_call(return_addr, self, call->function_name, arguments);
 							}
 						} else {
 							if (within_await) {
 								gen->write_call_self_async(result, call->function_name, arguments);
 							} else {
-								gen->write_call_self(result, call->function_name, arguments);
+								gen->write_call_self(return_addr, call->function_name, arguments);
 							}
 						}
 					} else if (callee->type == GDScriptParser::Node::SUBSCRIPT) {
@@ -579,12 +582,12 @@ GDScriptCodeGenerator::Address GDScriptCompiler::_parse_expression(CodeGen &code
 											gen->write_call_method_bind(result, base, method, arguments);
 										}
 									} else {
-										gen->write_call(result, base, call->function_name, arguments);
+										gen->write_call(return_addr, base, call->function_name, arguments);
 									}
 								} else if (base.type.has_type && base.type.kind == GDScriptDataType::BUILTIN) {
 									gen->write_call_builtin_type(result, base, base.type.builtin_type, call->function_name, arguments);
 								} else {
-									gen->write_call(result, base, call->function_name, arguments);
+									gen->write_call(return_addr, base, call->function_name, arguments);
 								}
 								if (base.mode == GDScriptCodeGenerator::Address::TEMPORARY) {
 									gen->pop_temporary();